The present invention relates to a process for controlling a color sorting machine which preferably processes agricultural products with the aid of a microprocessor. Light reflected from the product is directed to a photoelectric cell. Photoelectric cell output signals are fed into the microprocessor and compared with given values for known good products. When a variation between a photoelectric cell output signal and a given set value exists, an ejector is actuated, which discharges the relevant product. The invention also relates to an apparatus for performing the process.
U.S. Pat. No. 4,454,029 discloses a process of controlling a color sorting machine for agricultural products, e.g. coffee beans, peanuts, peas, etc. in such a way that each product is associated with a given background color corresponding to the product. The product to be sorted is then led past the background and illuminated from at least one light source. If the product color roughly corresponds with the given background, then a signal processing circuit provides no instruction to the ejector. Thus, the product remains on its conveying path. However, if the signal processing circuit establishes a color variation between the product and the background, a discharge instruction is produced for the ejector and is applied to the latter after appropriate signal conditioning and time lag. With a correct time lag matched to the conveying speed of the product, the ejector is then operated which, with a short, powerful air jet, then ejects the background-differing product from the run of conveyed products. The necessary control circuitry is constructed in conventional analog technology and TTL-logic and therefore corresponds to the prior art of the early seventies.